Originally, the traditional sandwich-making process required no apparatus whatsoever. In other words, with two pieces of bread and a filling, sandwiches were formed.
In two respects, the art of sandwich-making grew to require two alterations. The first related to the fact that with certain fillings, the fillings would leak through the side edges as the sandwich was being handled by the eater. The second related simply to the problems created by, generally, the varying styles of sandwiches that became part of modern fast-food and faddish culture, including the various hot sandwiches so popular today.
With respect to the former, an example of the problem presented by the original sandwich relates to the use; for instance, a sandwich filled with egg salad and lots of mayonnaise. Such a sandwich, especially if filled too much would be quite messy for the eater, the filling leaking from the side edges of the sandwich onto hands and clothes. An example of the second type of sandwich is probably best exemplified by sandwiches which use pita bread and a salad filling, wherein the walls of the pita bread are so thin as to lead to the same type of mess as previously described herein. In other words, the walls break, and the filling, whatever it is, leaks through the cracks and openings in the pita bread.
As a backdrop to all of the foregoing, waffle-irons, in traditional form, have been a staple apparatus in food kitchens all around the world. However, a waffle-iron, in its traditional shape, although an excellent apparatus for cooking and shaping waffles, is not particularly useful for making sandwiches, since the waffle pattern of indentations and protrusions provides too thin of a cover for the filling, and also makes cutting into two slabs very difficult.